JP2003267230A - Cable type steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cable type steering device to vary the steering gear ratio according to the position of a steering wheel. <P>SOLUTION: Operational cables 15 and 16 are spirally wound around an outer circumferential surface of a drive pulley 59 which is connected to and rotated by the steering wheel and an outer circumferential surface of a driven pulley which is connected to and rotated by a steering gear box to steer wheels, and the steering torque input in the steering wheel is transmitted to the steering gear box via the operational cables 15 and 16. The drive pulley 59 has a barrel shape with a center portion in the axial direction of the large diameter and both end portions in the axial direction of the small diameter, and the driven pulley has a spool shape or a drum shape with a center portion in the axial direction of the small diameter and both end portions in the axial direction of the large diameter. The steering gear ratio (the ratio of the steering angle of the steering wheel to the turning angle of the wheels) is changed according to the position of the steering wheel. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable type steering device in which a steering handle and a steering gear box are connected by a flexible operating cable such as a Bowden cable.

[0002]

2. Description of the Related Art Such a cable type steering device is
For example, JP-A-2000-25623 and JP-A-10-
It is known from Japanese Patent No. 59197 and Japanese Patent Laid-Open No. 8-2431.

By the way, the drive pulley and the driven pulley of this type of cable type steering device have the same cylindrical shape, and two operation cables are wound in a groove formed in a spiral shape on the outer peripheral surface thereof. When the steering handle is operated, one of the operation cables is taken up by the drive pulley and drawn out from the driven pulley, and the other operation cable is taken out from the drive pulley and taken up by the driven pulley, so that the rotation of the drive pulley is driven. It is transmitted to the pulley.

[0004]

By the way, since the driving pulley and the driven pulley of the conventional cable type steering device have the same cylindrical shape, the steering gear ratio (steering angle of steering wheel / The steering angle of the wheels) was constant, and it was not possible to sharpen or dull the steering characteristics depending on the position of the steering wheel.

The present invention has been made in view of the above circumstances, and an object thereof is to make a steering gear ratio variable in a cable type steering device according to the position of a steering wheel.

[0006]

In order to achieve the above object, according to the invention described in claim 1, an outer peripheral surface of a drive pulley which is connected to a steering handle and rotates,
A cable that spirally winds an operation cable around the outer surface of a driven pulley that is connected to the steering gear box that steers the wheels and that rotates, and that transmits the steering torque that is input to the steering wheel to the steering gear box through the operation cable. A cable type steering device is proposed, in which the driving pulley and the driven pulley have different busbar shapes.

According to the above construction, the busbar shape of the drive pulley and the busbar shape of the driven pulley are made different, so that the steering gear ratio can be changed according to the position of the steering wheel.

According to the invention described in claim 2,
In addition to the structure of claim 1, the drive pulley has a large diameter in the central portion in the axial direction and a small diameter at both ends in the axial direction, and the driven pulley has a small diameter in the central portion in the axial direction and a large diameter at both end portions in the axial direction. A characteristic cable type steering device is proposed.

According to the above construction, the drive pulley has a large diameter in the central portion in the axial direction and a small diameter at both end portions in the axial direction, and the driven pulley has a small diameter in the central portion in the axial direction and large diameters at both end portions in the axial direction.
The steering gear ratio can be progressively increased as the steering handle is operated from the neutral position toward the end position.

According to the invention described in claim 3,
In addition to the constitution of claim 1, the drive pulley has a small diameter in the central portion in the axial direction and a large diameter at both ends in the axial direction, and the driven pulley has a large diameter in the central portion in the axial direction and a small diameter at both end portions in the axial direction. A characteristic cable type steering device is proposed.

According to the above construction, the drive pulley has a small diameter in the central portion in the axial direction and a large diameter at both end portions in the axial direction, and the driven pulley has a large diameter in the central portion in the axial direction and a small diameter at both end portions in the axial direction.
The steering gear ratio can be progressively reduced as the steering handle is operated from the neutral position toward the end position.

According to the invention described in claim 4,
In addition to the configuration according to any one of claims 1 to 3, a cable type including an actuator that inputs a steering assist torque to a steering gear box according to a steering torque input to a steering handle. A steering device is proposed.

According to the above construction, the actuator is driven according to the steering torque input to the steering handle, so that the assist torque of the actuator is input to the steering gear box to reduce the load applied to the operation cable, thereby reducing the load on the operation cable. It is possible to suppress variation in the steering gear ratio due to stretching.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below based on the embodiments of the present invention shown in the accompanying drawings.

1 to 8 show a first embodiment of the present invention. FIG. 1 is an overall perspective view of a cable type steering device, FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. 1, and FIG. 2 of FIG.
-3 line sectional view, FIG. 4 is a perspective view of the steering torque sensor, FIG.
6 is a circuit diagram of a differential transformer of the steering torque sensor, FIG. 6 is an explanatory view of the operation of the steering torque sensor, FIG. 7 is an enlarged sectional view taken along line 7-7 of FIG. 1, and FIG. 8 shows a relationship between a steering angle and a steering gear ratio. It is a graph shown.

As shown in FIG. 1, a drive pulley casing 12 provided in front of a steering wheel 11 of an automobile.
And a driven pulley casing 14 provided above the steering gear box 13 are connected by two operation cables 15 and 16 made of Bowden cables. The tie rods 17L and 17R extending from the both ends of the steering gear box 13 in the left-right direction of the vehicle body are attached to the left and right wheels W.
It is connected to a knuckle (not shown) that supports L and WR. A steering torque sensor for detecting a steering torque input to the steering handle 11 is built in the drive pulley casing 12, and the driven pulley casing 14 and the driven pulley casing 14 are controlled by a controller 18 to which the detected steering torque is input. The actuator 20 provided in the integrated gear casing 19 operates to assist the driver's steering operation.

As shown in FIG. 2, the drive pulley casing 12 includes a rear housing 21 and a center housing 22.
The front housing 23 is connected with bolts 24, and the front cover 25 is connected to the front surface of the front housing 23 with a bolt (not shown). In the drive pulley casing 12, a bracket 21a provided on the rear housing 21 is fixed to the mounting stay 26 by a pin 27, and a bracket 23a provided on the front housing 23 is fixed to the mounting stay 26 with a bolt 28.

The hollow steering shaft 29 connected to the steering handle 11 is rotatably supported on the rear housing 21 by two ball bearings 30 and 31. A metal pulley boss 33 is fixed to the outer circumference of a hollow pulley shaft 32 arranged coaxially with the steering wheel 11. The drive pulley main body made of synthetic resin covers the serration portion 33a formed on the outer circumference of the pulley boss 33. 34 is integrally molded. Both ends of the pulley boss 33 are rotatably supported by the front housing 23 and the front cover 25 by two ball bearings 35 and 36, respectively, and the pulley shaft 32 is supported by the ball bearing 37 in the center housing 22.
Is rotatably supported by. The pulley boss 33 and the drive pulley body 34 form the drive pulley 59 of the present invention.

The front end inner circumference of the steering shaft 29 is relatively rotatably fitted to the outer circumference of the rear end of the pulley shaft 32, and the hollow portion of the steering shaft 29 and the hollow portion of the pulley shaft 32 are fitted to the torsion bar 38. Both ends are fitted and connected by pins 39 and 40, respectively. Therefore, the steering torque input to the steering shaft 29 is transmitted from the steering shaft 29 to the torsion bar 38.
Will be transmitted to the pulley shaft 32 via
A steering torque sensor 41 provided inside the center housing 22 detects the steering torque based on the amount of twist of the torsion bar 38.

As is apparent from FIGS. 2 and 4, the steering torque sensor 41 includes a cylindrical slider 42 supported on the outer periphery of the pulley shaft 32 so as to be relatively non-rotatable and slidable in the axial direction, and a steering shaft 29. A guide pin 43 that is fixed and fits into the inclined groove 42a formed in the slider 42, a magnetic ring 44 that is fixed to the outer circumference of the synthetic resin slider 42, and a magnetic ring that is fixed to the inner circumference of the center housing 22. There is provided a differential transformer 45 facing the motor 44, and a coil spring 46 for biasing the slider 42 forward so as to prevent looseness between the guide pin 43 and the inclined groove 42a.

As shown in FIG. 5, the steering torque sensor 41
The differential transformer 45 includes a primary coil 48 connected to an AC power supply 47, a first secondary coil 49, and a second secondary coil 50, and the magnetic ring 44 has first and second secondary coils. A movable iron core arranged between the next coils 49 and 50 is configured.

As is apparent from FIG. 2, the front end portion of the pulley shaft 32 and the pulley boss 33 are joined at the serration joint portion 51, and the pulley shaft 32 is
Are coupled via a tapered coupling portion 52 that tapers toward the front end of the. A nut 53 is screwed into the front end of the pulley shaft 32, and the load from the nut 53 urges the pulley boss 33 rearward along the pulley shaft 32 so that the taper coupling portion 52 is brought into close contact with a sufficient surface pressure. The pulley shaft 32 and the pulley boss 33 can be firmly integrated. As a result, it is possible to eliminate the influence of minute backlash existing in the serration coupling portion 51, suppress the generation of noise, and improve the steering feeling. When the nut 53 is tightened, the drive pulley 59 can move in the axial direction, so that an unreasonable load is prevented from being applied to the drive pulley casing 12.

As is apparent from FIGS. 2 and 3, the two operation cables 15 and 16 are made of a synthetic resin outer tube 15 formed by molding a coil spring having a substantially rectangular cross section.
o, 16o and inner cables 15i, 16i made of a twisted metal wire slidably housed therein. Two inner cables 15i, 16i
The short columnar pins 54, 54 fixed to the end portions of the two are fitted into the pin holes 34a, 34a formed on both end surfaces of the drive pulley body 34, and the two inner cables 15i, 16i extending from the pins 54, 54 are After being wound in a direction in which they approach each other along one spiral groove 34b formed on the outer periphery of the drive pulley main body 34, they are drawn out in a direction orthogonal to the axis of the pulley shaft 32.

The bottoms of the pin holes 34a, 34a of the drive pulley body 34 made of synthetic resin reach the boundary between the serration portion 33a of the pulley boss 33 and the drive pulley body 34, and with the pins 54, 54 removed, The boundary portion can be easily visually checked. Therefore, it is possible to reliably detect a processing error such as the drive pulley main body 34 being molded in an improper state in which the serrated portion 33a is not formed on the pulley boss 33.

Two cylindrical connecting portions 23b, 23b are formed in the front housing 23, and the boss portions 56a, 56a of the outer tube connecting members 56, 56 are fixed inside them. Pipe part 56 extending from the boss parts 56a, 56a to the outside of the connection parts 23b, 23b
b and 56b are fitted to the outer peripheries of the outer tubes 15o and 16o, and the caulked portions 56c and 56c are caulked, whereby the ends of the outer tubes 15o and 16o are fixed to the front housing 23. Outer tube coupling member 56,
Guide bushes 57, 57 made of synthetic resin having good sliding properties are held on the inner circumferences of the boss portions 56a, 56a of 56 in order to prevent the inner cables 15i, 16i and the boss portions 56a, 56a from being directly rubbed. .

The connecting portion 23b of the front housing 23,
23b to the predetermined position of the outer tubes 15o and 16o of the operation cables 15 and 16 (for example, the pipe portions 56b and 56 of the outer tube coupling members 56 and 56).
(From b to the exposed portion) are covered with rubber covers 58, 58. The rubber covers 58, 58 having elasticity include the outer circumferences of the connecting portions 23b, 23b of the front housing 23,
Since the outer tubes 15o and 16o are closely adhered to the outer peripheries of the outer tubes 15 and sealing, the outer tubes 15o and 16o are joined to the front housing 23 by caulking portions 56c and 56c of the outer tube connecting members 56 and 56 and the outer tube connecting members 56 and 56. It is possible to prevent water from entering through the gaps between the boss portions 56a, 56a and the connecting portions 23b, 23b.

Since the two ball bearings 35 and 36 supporting the pulley boss 33 are of a waterproof type inside the front housing 23 and the front cover 25 which house the drive pulley 59, there is no risk of the drive pulley 59 getting wet. Since the drive pulley 59 and the outer tubes 15o and 16o are housed in the sealed space in this manner, the drive pulley casing 12 is arranged in the vehicle compartment and the drinking water that the occupant has spilled is splashed. Even when the outer tubes 15o and 16o and the inner cables 15i and 16i are slid, the water freezes at a low temperature and the smooth movement of the operation cables 15 and 16 is hindered.
It is possible to prevent the durability of the operation cables 15 and 16 from being deteriorated by i and 16i rusting.

As shown in FIG. 7, the driven pulley casing 14 is composed of an upper housing 61 and a lower housing 62 which are connected by bolts (not shown), and the gear casing 19 includes a gear casing main body 63 and a gear casing main body 63. The lower housing 62 and the upper cover 64 are connected to each other with a plurality of bolts 65 ...

A ball bearing 66 provided in the upper housing 61, a ball bearing 67 provided in the lower housing 62, two ball bearings 68 and 69 provided in the gear casing main body 63, and a pulley shaft 70.
Is rotatably supported. The upper two ball bearings 66, 67 do not directly support the pulley shaft 70, but support the pulley boss 71 fixed to the outer periphery of the pulley shaft 70. The ball bearing 66 provided in the upper housing 61 is retained by an annular nut 72, and the lower ball bearing 69 provided in the gear casing main body 63 is retained by a bag-shaped nut 73.

The upper end portion of the pulley shaft 70 and the pulley boss 71 are joined at a serration joint portion 74 and also via a tapered joint portion 75 which is tapered toward the upper end portion of the pulley shaft 70. A nut 76 is screwed onto the upper end of the pulley shaft 70,
By urging the pulley boss 71 downward along the pulley shaft 70 by the load from the nut 76, the taper coupling portion 75 is brought into close contact with the pulley shaft 70 with sufficient surface pressure, and
By firmly integrating the pulley boss 71 with each other, it is possible to eliminate the influence of minute play existing in the serration joint portion 74, suppress the generation of noise, and improve the steering feeling. When the nut 76 is tightened, the driven pulley 60 can move in the axial direction, so that an unreasonable load is prevented from being applied to the driven pulley casing 14 and the gear casing 19.

The serration portion 7 on the outer periphery of the pulley boss 71
A driven pulley main body 77 made of a synthetic resin is integrally molded in 1a, and short cylindrical pins 78, 78 fixed to the ends of the inner cables 15i, 16i of the two operation cables 15, 16 are driven pulley main bodies. Two inner cables 15i, 16i fitted in pin holes 77a, 77a formed on both end surfaces of 77 and extending from the pins 78, 78 are formed along one spiral groove 77b formed on the outer periphery of the driven pulley body 77. After being wound in a direction in which they approach each other, they are pulled out in a direction orthogonal to the axis of the pulley shaft 70. The pulley boss 71 and the driven pulley body 77 constitute the driven pulley 60 of the present invention.

The bottoms of the pin holes 77a, 77a of the driven pulley body 77 made of synthetic resin reach the boundary between the serrated portion 71a of the pulley boss 71 and the driven pulley body 77, and when the pins 78, 78 are removed, The boundary portion can be easily visually checked. Therefore, it is possible to reliably find a processing error such as the driven pulley body 77 being molded in a state where the serrated portion 71a is not formed on the pulley boss 71.

The driven pulley casing 14 is formed with two cylindrical connecting portions 14a, 14a, and the boss portions 79a, 79a of the outer tube connecting members 79, 79 are fixed inside them. Bosses 79a, 79a
Pipe portion 79 extending from the outside to the connection portions 14a, 14a
b and 79b are fitted to the outer peripheries of the outer tubes 15o and 16o, and the caulked portions 79c and 79c are caulked, whereby the ends of the outer tubes 15o and 16o are fixed to the driven pulley casing 14. Outer tube connecting member 7
On the inner circumferences of the boss portions 79a, 79a of 9, 79, there are held guide bushes 80, 80 made of synthetic resin having good sliding property so as to prevent the inner cables 15i, 16i and the boss portions 79a, 79a from directly rubbing. To be done.

From almost the entire driven pulley casing 14 through the connecting portions 14a, 14 to the operation cables 15, 16
The outer tubes 15o and 16o are covered with a single rubber cover 81 up to a predetermined position (for example, from the pipe portions 79b and 79b of the outer tube coupling members 79 and 79 to exposed portions). The rubber cover 81 allows the outer tube connecting member 7 through which water is most likely to enter.
Not only can the caulked portions 79c and 79c of 9, 79 be reliably sealed, but also the ball bearing 6 that supports the split surfaces of the upper housing 61 and the lower housing 62 of the driven pulley casing 14 and the upper end of the pulley shaft 70.
It is also possible to prevent the infiltration of water from 6.

As a result, the waterproofness of the driven pulley casing 14 arranged in the lower part of the engine room and more easily wet with water than the drive pulley casing 12 can be enhanced, and the outer tubes 15o and 16o and the inner cables 15i and 16i can be improved. Moisture attached to the slide parts of the inner cables 15i, 16 may be blocked by freezing of the operation cables 15, 16 at low temperatures, and the inner cables 15i, 16
It is possible to prevent i from rusting and lowering the durability of the operation cables 15 and 16.

At the upper part of the gear casing 19, which is sealed between the driven pulley casing 14 and the driven pulley casing 14, a worm wheel 82 fixed to the pulley shaft 70 and an actuator 2 composed of an electric motor are provided.
Worm 83 fixed to the output shaft 20a of 0 (see FIG. 1)
And are in mesh. The steering gear box 13 is attached to the pinion 84 formed on the lower portion of the pulley shaft 70.
The rack 85 (see FIG. 1) is meshed, and the rack 85 is urged toward the pinion 84 at the meshing portion.

That is, the slide member 86 is slidably fitted into the through hole 63a formed in the gear casing main body 63 through the O-ring 87, and the spring seat 88 and the slide member 86 screw-connected to the through hole 63a. The low-friction member 90 provided on the slide member 86 comes into contact with the back surface of the rack 85 by the elastic force of the coil spring 89 arranged between them. As a result, when the rotation of the pulley shaft 70 is transmitted to the rack 85 via the pinion 84 and the wheels WL and WR are steered, the rack 85 is prevented from rattling or bending without receiving a large sliding resistance. It can be operated smoothly.

As is apparent from a comparison of FIGS. 2 and 7, the drive pulley 59 has a barrel-like shape with the largest diameter in the axial center portion and gradually decreasing from it toward both axial end portions. The driven pulley 60 is formed in a pincushion shape or a drum shape in which the diameter at the central portion in the axial direction is the smallest and the diameter gradually increases from the central portion toward the both end portions in the axial direction. That is, the generatrix of the drive pulley 59 made of a rotating body is an arc-shaped curve whose central portion in the axial direction bulges outward, and the generatrix of the driven pulley 60 made of a rotating body is an arc-shaped curve whose central portion in the axial direction is depressed inward. Is a curve,
The shapes of both busbars are complementary to each other, that is, complementary.

Next, the operation of the embodiment of the present invention having the above construction will be described.

The steering torque detected by the steering torque sensor 41 is input to the control device 18, and the control device 18 controls the operation of the actuator 20 based on the steering torque. That is, when the steering handle 11 is operated to turn the vehicle, the steering torque is transmitted to the pulley shaft 32 via the steering shaft 29 and the torsion bar 38 and is wound around the drive pulley main body 34, as shown in FIG. The inner cables 15i, 16i of the cables 15, 16 are pulled and the other inner cables 15i, 16i are loosened, whereby the rotation of the drive pulley 59 is transmitted to the driven pulley 60. As a result, the pulley shaft 70 shown in FIG. 7 rotates, and the wheels WL, WR pass through the pinion 84, the rack 85, and the tie rods 17L, 17R in the steering gear box 13.
The steering torque is transmitted to.

When the steering torque is not input to the steering wheel 11, the torsion bar 38 is not twisted and deformed, the steering shaft 29 and the pulley shaft 32 are held in the same phase, and as shown in FIG. The guide pin 43 of the shaft 29 is the inclined groove 42.
At the center of a, the slider 42 is held at the vertical center position. At this time, as shown in FIG.
The magnetic ring 44 provided on the secondary coil 4 is located at an intermediate position between the first secondary coil 49 and the second secondary coil 50.
It is detected that the output voltages of 9, 50 are equal and the steering torque is zero.

When the steering handle 11 is operated to the right and steering torque in the direction of arrow a in FIG. 6A is input to the steering shaft 29, the torsion bar 38 is twisted and deformed, and the steering shaft 29 and the pulley shaft are deformed. Since a phase difference is generated between the slider 32 and the slider 32 (ie, the slider 42 that cannot rotate relative to the pulley shaft 32), the guide pin 43 of the steering shaft 29 pushes the inclined groove 42a to slide the slider 42 upward. . As a result, the output voltage of the upper first secondary coil 49 increases and the output voltage of the lower second secondary coil 50 decreases, and the steering torque in the right turning direction is detected based on the voltage difference. It Similarly, the steering handle 11 is operated to the left to move the steering shaft 29 to the steering shaft 29 as shown in FIG.
When the steering torque is input in the direction of arrow b in (C), the torsion bar 38 is twisted and deformed, and a phase difference is generated between the steering shaft 29 and the pulley shaft 32 (that is, the slider 42). 29
4 in which the inclined groove 42a is pressed by the guide pin 43 of
2 slides down. As a result, the output voltage of the upper first secondary coil 49 decreases and the output voltage of the lower second secondary coil 50 increases, and the steering torque in the left turning direction is detected based on the voltage difference. It

As described above, when the steering torque sensor 41 detects the steering torque, the control device 18 drives the actuator 20 so that the steering torque detected by the steering torque sensor 41 is held at a predetermined value. To do. As a result, the torque of the actuator 20 is transmitted to the pulley shaft 70 via the worm 83 and the worm wheel 82.
And the steering wheel operation by the driver is assisted. As a result, the load applied to the inner cables 15i and 16i of the operation cables 15 and 16 can be reduced, and the extension thereof can be minimized to prevent deterioration of the steering feeling. By combining the steering torque sensor 41 having the differential transformer 45 and the actuator 20, the actuator 20 can be operated only by electrical control, and the structure of the control system is simplified.

Since the drive pulley 59 has a barrel shape and the driven pulley 60 has a pincushion shape or an hourglass shape, the effective diameter of the drive pulley 59 when the steering handle 11 is near the neutral position. At maximum, the effective diameter of the driven pulley 60 is minimized, resulting in a minimum steering gear ratio (steering wheel steering angle / wheel steering angle). On the other hand, when the steering handle 11 is near the end position, the effective diameter of the drive pulley 59 is minimized and the effective diameter of the driven pulley 60 is maximized, resulting in a maximum steering gear ratio.

FIG. 8 shows the above relationship of the steering gear ratio with respect to the steering angle. If the driving pulley 59 and the driven pulley 60 are both cylindrical with the same diameter, that is, if the generatrix is a straight line parallel to the rotation axis, the steering gear ratio is constant regardless of the steering angle (rack). 8
5 and the gear ratio of the pinion 84). However, in this embodiment, the steering gear ratio becomes small near the neutral position of the steering handle 11 and the steering characteristic becomes sensitive, and the steering gear ratio becomes large near the end position and the steering characteristic becomes insensitive. Therefore, if the present embodiment is applied to a vehicle having an oversteer characteristic, the steering characteristic becomes progressively insensitive as the steering angle of the steering handle 11 increases, so that the oversteer characteristic is corrected to a neutral steer characteristic. You can

As described above, the desired steering characteristics can be obtained by progressively changing the steering gear ratio by simply changing the shapes of the driving pulley 59 and the driven pulley 60.

Next, a second embodiment of the present invention will be described with reference to FIGS.

The second embodiment differs from the first embodiment in the shapes of the driving pulley 59 and the driven pulley 60, and the other structures are the same as those in the first embodiment.

The busbar of the drive pulley 59 of the second embodiment bulges outward at the center in the axial direction and is parallel to the rotary shaft at both ends in the axial direction, and the busbar of the driven pulley 60 is inward at the center in the axial direction. The dent is parallel to the rotation axis at both ends in the axial direction, and both busbars have complementary shapes. As a result, FIG.
In the steering gear ratio characteristic shown in Fig. 3, the steering gear ratio becomes large near the neutral position of the steering handle 11 and the steering characteristic becomes insensitive, and the steering gear ratio becomes a small constant value near the end position and the steering characteristic becomes small. Be sensitive. Therefore, if this embodiment is applied to a vehicle having an understeer characteristic, the steering characteristic becomes more sensitive as the steering angle of the steering handle 11 increases, so that the understeer characteristic can be corrected to the neutral steer characteristic.

Although the embodiments of the present invention have been described in detail above, the present invention can be modified in various ways without departing from the scope of the invention.

For example, the generatrix of the drive pulley 59 and the generatrix of the driven pulley 60 do not necessarily have to be complementary shapes, as long as the shapes of both busbars are different, and the shape of the generatrix need not necessarily be a curve.

To give some examples, the drive pulley 59
Also, one of the driven pulleys 60 may be barrel-shaped and the other pulley may be bobbin-shaped or hourglass-shaped, and the curvatures may be different without being complementary shapes. Further, one of the driving pulley 59 and the driven pulley 60 may be barrel-shaped and the other may be cylindrical.
One may have a pincushion shape or a drum shape, and the other may have a cylindrical shape. Further, both the drive pulley 59 and the driven pulley 60 may be barrel-shaped, and only their curvatures may be different, or both the drive pulley 59 and the driven pulley 60 may be pincushion-shaped or hourglass-shaped, and their curvatures may be different. Is also good. That is, according to the present invention, the drive pulley 59 and the driven pulley 60 are included.
All variations are included except those having the same shape.

[0053]

As described above, according to the invention described in claim 1, since the shape of the busbar of the driving pulley and the shape of the busbar of the driven pulley are made different, the steering gear ratio is changed according to the position of the steering wheel. Can be changed.

According to the invention described in claim 2,
The drive pulley has a large diameter in the central part in the axial direction and a small diameter at both ends in the axial direction, and the driven pulley has a small diameter in the central part in the axial direction and large diameters at both ends in the axial direction, so the steering handle is moved from the neutral position to the end position. The steering gear ratio can be progressively increased as it is operated toward.

According to the invention described in claim 3,
Since the drive pulley has a small diameter in the axial center and large diameters at both ends in the axial direction, and the driven pulley has a large diameter in the axial center and small diameters at both axial ends, the steering handle is moved from the neutral position to the end position. The steering gear ratio can be progressively reduced as it is operated toward.

According to the invention described in claim 4,
Since the actuator is driven according to the steering torque input to the steering wheel, the assist torque of the actuator is input to the steering gear box to reduce the load applied to the operation cable and suppress the fluctuation of the steering gear ratio due to the extension of the operation cable. can do.

[Brief description of drawings]

FIG. 1 is an overall perspective view of a cable type steering device.

FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG.

3 is a sectional view taken along line 3-3 of FIG.

FIG. 4 is a perspective view of a steering torque sensor.

FIG. 5 is a circuit diagram of a differential transformer of a steering torque sensor.

FIG. 6 is an operation explanatory view of a steering torque sensor.

7 is an enlarged sectional view taken along line 7-7 of FIG.

FIG. 8 is a graph showing the relationship between the steering angle and the steering gear ratio.

FIG. 9 is a diagram corresponding to FIG. 2 according to the second embodiment.

FIG. 10 is a diagram corresponding to FIG. 7 according to the second embodiment.

FIG. 11 is a graph showing the relationship between the steering angle and the steering gear ratio.

[Explanation of symbols]

11 steering wheel 13 Steering gear box 15 Operation cable 16 Operation cable 20 actuators 59 Drive pulley 60 driven pulley WL wheel WR wheels

Claims (4)

[Claims] 1. An outer peripheral surface of a drive pulley (59) which is connected to a steering handle (11) and rotates, and a wheel (W).
Steering gear box (1 for steering L, WR)
3) The operation cables (15, 16) are spirally wound around the outer peripheral surface of the driven pulley (60) which is connected to and rotates.
A cable type steering device for transmitting a steering torque input to a steering handle (11) to a steering gear box (13) through an operation cable (15, 16), in which a shape of a bus bar of a drive pulley (59) and a driven pulley ( 6
0) A cable type steering device characterized in that the shape of the bus bar is different. 2. The drive pulley (59) has a large diameter in the central part in the axial direction and a small diameter at both ends in the axial direction, and the driven pulley (60) has a small diameter in the central part in the axial direction and large diameters at both ends in the axial direction. The cable type steering device according to claim 1, wherein: 3. The drive pulley (59) has a small diameter in the central portion in the axial direction and a large diameter at both ends in the axial direction, and the driven pulley (60) has a large diameter in the central portion in the axial direction and a small diameter at both end portions in the axial direction. The cable type steering device according to claim 1, wherein: 4. A steering gear box (1) according to a steering torque input to a steering handle (11).
The cable type steering device according to any one of claims 1 to 3, further comprising an actuator (20) for inputting a steering assist torque.